Annite is a dark, iron-rich member of the mica group commonly found in igneous rocks like granites and syenites. It is easily recognized by its dark, often black, micaceous sheets that show perfect cleavage, though it is often chemically indistinguishable from other biotite-series minerals without laboratory analysis.

Hardness

2.5-3

Mohs

Luster

Pearly

Streak

White

Transparency

Opaque

mineralcommonBiotite Group family

Annite

Hardness: 2.5-3
Luster: Pearly
Streak: White
Transparency: Opaque

Is this annite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch annite with a known reference. Annite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Annite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Annite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: black, dark brown, dark green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, foliated masses, micaceous scales.

Often confused with

Annite vs. its common look-alikes — and how to tell them apart in the field.

Often found alongside annite

Minerals reported to co-occur with annite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: KFe₃AlSi₃O₁₀(OH)₂
Mohs hardness: 2.5-3
Density: 3.1-3.3 g/cm³
Colors: Black Dark Brown Dark Green
Streak: White
Luster: Pearly
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Tabular Crystals, Foliated Masses, Micaceous Scales
Cleavage: Perfect Basal
Rarity: Common
Uses: Collector, Scientific Research
Host rock: Granite Pegmatites, Syenites
Typical price: $10-50 for hand-sized specimens

Where rockhounds find annite

Classic worldwide localities

Rockport, Massachusetts, USA
Pikes Peak, Colorado, USA
Cape Ann, Massachusetts, USA
Kola Peninsula, Russia

Field-hunting tip

Look in granite pegmatites, syenites country — that is the host setting where annite typically forms. If you start seeing quartz, k-feldspar, zircon in float, you are in the right ground. Field specimens usually show a tabular crystals, foliated masses, micaceous scales habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify annite?+

Mohs hardness is 2.5-3. It typically shows a pearly luster. The streak is white. Common colors include black, dark brown, dark green.

Where is annite found?+

Notable localities include Rockport, Massachusetts, USA; Pikes Peak, Colorado, USA; Cape Ann, Massachusetts, USA; Kola Peninsula, Russia.

How much is annite worth?+

Typical asking prices fall in the range of $10-50 for hand-sized specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like annite?+

Annite is most often confused with Phlogopite, Siderophyllite, Muscovite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with annite?+

Annite commonly co-occurs with Quartz, K-feldspar, Zircon, Magnetite, Fluorite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does annite form in?+

Annite typically forms in granite pegmatites, syenites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is annite used for?+

Annite is used in collector, scientific research.

Find annite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.